Orchard-grown seedlings can provide growth gain

By Paul Morgan

During the late 1960s and early 1970s, orchards were established throughout the Pacific Northwest to produce Douglas-fir seed from selected parent trees. Orchards were started by public and private forestry organizations. Some were cooperative ventures of various landowners within a region, such as the Vernonia Co-op. Major forest landowners - private, state and federal - were convinced that the high costs of a tree improvement program with the selection of parents and the establishment of progeny test sites and orchards would be offset by gains in volume growth of future plantations.

Seed orchards were designed to produce large amounts of seed from diverse parents that exhibited high volume growth traits. Progeny from these parents were grown and planted in special sites in the forest to determine the actual growth over a number of years. Data from these progeny test sites was used to rank parents from the slowest to fastest volume growth after 5, 10 and 15 years. Some parents that grew poorly or produced progeny with poor form were removed from the orchard or "rogued out." This selection process would enhance the growth of the progeny from the remaining parents.

Douglas-fir has been the predominant species of most tree improvement programs in the Northwest. Seed orchards produce hundreds of pounds of Douglas-fir seed each year from selected parents from many regions in Oregon and Washington. These regions or breeding zones are geographic areas where progeny test sites should be well adapted to local growing conditions of climate and soils. Other species, like western hemlock, ponderosa pine and lodgepole pine, have also been included in more limited tree improvement programs with similar volume growth goals of the Douglas-fir programs.

Orchard seed is identified by ranked parents so that it can be mixed in special blends of families to produce broadly adapted high performance seedlings. Depending on how the seed is mixed, differing amounts of additional growth can be expected above natural or wild collections of seed. Most Douglas-fir tree improvement programs claim that a typical first generation improved orchard seed mix available to family forest landowners could exhibit a 10 percent gain in volume growth.

Tree improvement program members are committed to the intensive management required of these improved plantations. In this process, while you pay a few pennies more for each improved seedling, it is the least expensive cost in comparison to the costs of intensive site preparation, planting, animal damage protections and fertilization before or after planting. These reforestation practices are necessary to allow the seedlings to fully express their superior growth attributes. The goal is to provide a site without vegetation competition or animal damage with ample nutrients to promote very rapid growth to a "free to grow" state. Trees are considered free to grow when they dominate the site, generally achieving a height of six feet with shoots well above any competing trees or brush.

Improved seed available

Family forest landowners can also obtain seedlings grown from improved orchard seed. Both the Washington State DNR Webster Forest Nursery near Olympia and the Oregon Department of Forestry's Phipps Forest Nursery near Elkton sell genetically improved seedlings each year. Some private nurseries in the Northwest also sell improved seedlings, but most do so only if extra seedlings are released by contract growers.

Do genetically improved seedlings appear different from "wild" seed source seedlings? Not really. Improved Douglas-fir and western hemlock grown at Phipps Nursery don't look like special "super" trees. In the nursery bed the improved seedlings grow quickly into large, robust trees with good foliage density and color. The native source seedlings also grow into large healthy trees with ample foliage and dark green color. A subtle difference can be seen in the beds and at harvest - the genetically improved seedlings are more uniform in size and form.

When it developed the Schroeder Seed Orchard near St. Paul, the Oregon Department of Forestry had the vision to set aside a small portion of the annual seed production for family forest landowners in Oregon. This seed, mostly Douglas-fir, but also western hemlock, is purchased by the Phipps Nursery to be grown for family forest landowners. Each year, the staff at Phipps Nursery plants seed mixes of improved Douglas-fir and western hemlock for northern and central western Oregon. Two years later, either 2+0 or 1+1 transplant seedlings are for sale. Due to the high cost of the orchard seed, these seedlings may cost $20 or $30 per thousand seedlings more than wild seed source seedlings. That translates to just two or three cents more per tree for a seedling with great future growth potential. Family forest landowners that haven't had to invest thousands of dollars in tree improvement programs can, for a few extra cents a tree, reap the rewards of these programs.

Phipps Nursery offers family forest landowners a special year-round reservation system to retain improved and other seedlings months before planting by placing a small deposit. This allows landowners that can plan ahead to have an assurance that they will have the trees they need to replant. However, since seedlings can be bought throughout the year, even last-minute buyers may be able to wait for the best log prices prior to committing to a tree purchase. Generally, however, supplies of genetically improved orchard seedlings or limited, so last-minute buyers may find selection poor or not available until next year.

What's improved about improved seedlings?

Orchard seedlings are not all grown for rapid growth or wood quality. Some orchards were developed to complement a selection program to find disease tolerant or resistant progeny. The USDA Forest Service operates an orchard near Dorena, Ore., to raise seed from parents that display various levels of resistance to white pine blister rust, a forest tree disease that affects native five-needle pines. The primary goal is not rapid growth, but healthy white pine and sugar pine seedlings for the forests of Oregon. A new project may soon yield parent Port Orford cedars that have resistant traits to the lethal root disease caused by Phytophthora lateralis. Pine seedlings resistant to blister rust are generally available from Phipps Nursery and a few other sources as surplus seedlings. As with other orchard seedlings, these disease-resistant species may cost a few cents extra per tree.

Some newer orchards were developed with a primary goal of gene conservation. Generally these orchard species are considered at risk within a certain range, so gathering genetic material and bringing it into an orchard is a method of retaining genetic diversity. Several species, such as noble fir, grand fir, western redcedar and incense cedar have been brought into this type of genetic preservation.

The Oregon Department of Forestry, in cooperation with the Willamette Valley Ponderosa Pine Association, has established a new addition to the Schroeder Seed Orchard - a valley pine orchard. This orchard will preserve a diverse genetic base of valley ponderosa pines for future generations. It will also produce a consistent supply of seed for a population that has infrequent seed crops and suffers greatly from cone insect attacks in native stands. Unfortunately, no seed is available yet. However, within the next five to eight years, family forest landowners should be able to obtain selected orchard valley pine seedlings from several nurseries in Oregon.

Not all seedlings produced from orchards are conifer, some are hardwoods, like poplars. Breeding programs with hybrid poplars began in 1978 at Washington State University. Researchers transferred pollen from selected parents to the flowers of others to produce special crosses that would have superior growth rates and form. These fast growing hybrids could be reproduced by taking cuttings of the shoots. Each cutting was genetically identical (a clone) to the original poplar hybrid. Since poplars mature quickly, several generations of improved poplars have been bred and tested since the program began. The second generation focused on developing new clones with resistance to native or introduced diseases. The breeding program continues at the University of Washington to develop new clones with special adaptation for broader use of poplars in the Pacific Northwest.

Poplar improvement programs have been designed to not only find very fast growing clones but to also have offspring with resistance to various foliage and stem diseases like rusts and cankers. New programs will seek poplars that tolerate herbicides to allow vegetation control of competing brush or grasses. Rather than planting seeds, nurseries plant cuttings to grow either more cuttings or rooted cuttings of the hybrid poplar clones. Several private and public nurseries in the Northwest sell newer clonal cuttings and a few sell rooted cuttings.

Paul Morgan is nursery manager at the Oregon Department of Forestry's D.L. Phipps Nursery in Elkton, Ore.

This article appeared in the Northwest Woodlands magazine, Winter 2000 - Published quarterly by the World Forestry Center for the Oregon Small Woodlands Association, Washington Farm Forestry Association, Idaho Forest Owners Association and Montana Forest Owners Association.